1. Field of the Invention
The present invention relates to a technique for extracting a desired area from an image.
2. Description of the Related Art
A technique called segmentation is known which separates a given image into a foreground (a portion to be extracted) and a background (the remaining portion) by means of digital image processing using a computer.
Quick and accurate segmentation is desired for a segmentation process. According to Patent Literature 1, the resolution of an image is set to be coarse initially and then enhanced gradually in accordance with the increasing number of updating a contour line. In this case, when the contour line is updated, new contour points are determined based on a rectangular area having a predetermined width and centered at a segment with which a reference point in an area in the image and a contour point are connected together.
In Non Patent Literature 1, a plurality of images with respective resolutions are prepared and segmented in order starting with an image with the lowest resolution. In Non Patent Literature 1, the level set algorithm is used. The level set processing can be quickly converged by using the result of processing of an image with a low resolution as an initial contour line for an image with the next resolution. Moreover, in this document processing speed is increased by using an image subjected to wavelet conversion as a target image for segmentation.